Abstract: Aldo Leopold, best known as the author of A Sand County Almanac, was a keen observer of the natural world. Throughout his life he kept daily journals recording observations of seasonal events, especially those occurring at his beloved "shack" on the Leopold farm which was the setting for many essays in A Sand County Almanac. Leopold's meticulous phenological observations have provided us with an unparalleled record of when plants bloomed, birds migrated and other natural events. Analyzing his historical observations of hundreds of natural events as well as recent records helps us understand how climate change is affecting the ecological community.